Bolus is used in radiation therapy to treat uneven areas of a patient, to make up for missing tissue, or to provide a build-up of dose to the skin surface.

Breast cancer patients who have undergone a total resection to remove all breast masses and then received radiation therapy are exposed to large amounts of radiation, which may damage the lungs which are adjacent to the treatment area. These patients are therefore at a higher risk for radiation pneumonitis.

To protect the lungs from radiation, patients wear the jacket-shaped device that is the bolus to block the radiation. However, because body types and chest size differs per patient, a “normal” bolus is not compatible for all patients, serving as a limitation in lesion treatment and in protecting the lungs.

The technology patent, developed independently by the Radiation Oncology Department at Gangnam Severance Hospital, allows for customized radiation therapy for every patient.

The research team began developing a bolus that fits precisely according to the patient's chest using CT scanning and 3D printing technology starting in 2016.

The Gangnam Severance team used CTs to distribute the virtual bolus and the affected area in a tile-like fashion and then calculated the radiation dose for each site. Based on this, researchers derived the size and shape of an optimal bolus and then created it with 3D printing technology.

Breast cancer patients sporting these boluses obtained optimal radiation therapy while getting protection for the areas not affected with cancer, the hospital said.

"Advanced technologies such as 3D printing have been developed with the implementation of high-precision radiation therapy. We believe that this is a good example of cross-functional research that increases the treatment effect for breast cancer patients while further lowering side effects," said Professor Lee Ik-jae from Gangnam Severance Hospital, Department of Radiation Oncology. "We hope further development of these technologies will help more cancer patients overcome their cancers."

A research paper on the recently obtained patent was published in the international Journal Oncotarget.